Infection with herpes simplex virus-1 (HSV-1) brings numerous changes in cellular gene expression. Levels of most host mRNAs are reduced, limiting synthesis of host proteins, especially those involved in antiviral defenses. The impact of HSV-1 on host microRNAs (miRNAs), an extensive network of short non-coding RNAs that regulate mRNA stability/translation, remains largely unexplored. Here we show that transcription of the miR-183 cluster (miR-183, miR-96, and miR-182) is selectively induced by HSV-1 during productive infection of primary fibroblasts and neurons. ICP0, a viral E3 ubiquitin ligase expressed as an immediate-early protein, is both necessary and sufficient for this induction. Nuclear exclusion of ICP0 or removal of the RING (really interesting new gene) finger domain that is required for E3 ligase activity prevents induction. ICP0 promotes the degradation of numerous host proteins and for the most part, the downstream consequences are unknown. Induction of the miR-183 cluster can be mimicked by depletion of host transcriptional repressors zinc finger E-box binding homeobox 1 (ZEB1)/δ-crystallin enhancer binding factor 1 (δEF1) and zinc finger E-box binding homeobox 2 (ZEB2)/Smad-interacting protein 1 (SIP1), which we establish as new substrates for ICP0-mediated degradation. Thus, HSV-1 selectively stimulates expression of the miR-183 cluster by ICP0-mediated degradation of ZEB transcriptional repressors.

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e19510 Background: Cytogenetic abnormalities (CA) carry prognostic significance in MM. Immunoglobulin isotypes also predict disease behavior, with non-IgG subtypes historically being associated with poorer outcomes. We hypothesized that MM non-IgG isotype and higher risk CA are associated with greater degree of marrow infiltration (BM%) and presence of end organ damage at presentation. Methods: 552 MM patients were retrospectively analyzed using a multi-institution repository of BM%, isotype, and CA risk groups stratified by mSMART criteria. A subset of 110 patients were used to assess clinical comparisons and associations between CA, isotype, and end organ damage using the chi-square or Fisher’s exact test for categorical variables and the Mann-Whitney test to compare between groups for continuous variables. Results: There was a higher BM% seen in the intermediate risk group compared to standard risk group (50% vs 20%, p < 0.04). A lower BM% was seen in the IgG subtype compared to other isotypes (27% vs 45%, p < 0.02). CA including del(13q), del(16q), dup(1p), dup(1q), t(4;14), t(11;14), and trisomy 11 were associated with a higher BM%. When comparing isotypes to CA risk groups, IgA isotype was associated with greater risk, including del(13q) and del(16q). IgG isotype was associated with trisomy 11, while light chain MM correlated with higher risk CA including del(17p), and dup(1q). Lytic lesions on presentation were more frequent in patients with trisomy 11 and less frequently in IgA MM. Anemia presented more in IgA MM, and renal failure in patients with t(14;16). Conclusions: Lower BM% was found in IgG isotype MM, which correlated with standard risk CA, whereas light chain MM was associated with higher risk CA; this risk group being more likely to present with renal failure. Unexpectedly, lytic lesions on presentation correlated with non-IgA isotype and better risk CA. Further studies are needed to confirm these findings prospectively to determine if they can predict end organ damage in patients with specific isotypes or CA groups.

Introduction: In multiple myeloma (MM), chromosomal abnormalities (CAs) are valuable in risk stratifying patients and predicting disease free survival. While immunoglobulin isotypes have historically contributed to MM staging, more recently established classifications of CAs have allowed for a revised staging system that better predicts disease behavior. In this retrospective study, we hypothesized that CAs correlate with disease characteristics including immunoglobulin heavy chain isotype, degree of bone marrow infiltration (PC%), and end-organ damage. Methods: MM patients diagnosed between 2013 to 2019 were included in this retrospective chart review using electronic records from two distinct sources: (1) 442 patients from an independent pathology database and (2) a validation cohort composed of 110 patients from our institution. CAs were stratified by Mayo mSMART 2.0 criteria into standard, intermediate, and high-risk groups (Mikhael et al. Mayo Clin Proc 2013). End-organ damage was defined as the presence of lytic bone lesions, anemia, hypercalcemia, or renal failure on clinical presentation. Within each cohort, associations between categorical variables were made using the chi-squared test or Fisher's exact test, as deemed appropriate. The Mann-Whitney test was used to compare between groups for continuous variables. A result was considered statistically significant at the p&lt;0.05 level of significance. All analyses were performed using SAS version 9.4 (SAS Institute Inc., Cary, NC). Results: 552 MM patients were included in the study. Multi-variate analysis revealed that del(13q14), dup(1q21), t(4;14), trisomy (11q13), del(16q23), and hypodiploidy were associated with a significantly higher PC%, whereas kappa light chain only (LCO) disease was associated with a lower PC%. Higher median PC% was found when comparing the intermediate to standard CA risk group. IgA isotype was associated with intermediate risk CAs including del(13q) and standard risk CAs including t(11;14), while IgG isotype was associated with dup(1q21), and kappa LCO disease correlated with a higher rate of higher risk CAs including deletion of p53 at 17p13 and dup(1q21). With regard to clinical presentation, lytic lesions were more frequent in patients with normal cytogenetics and trisomy 11 and less frequent in IgA isotype, whereas the presence of anemia on presentation correlated with IgA isotype. Renal failure was associated with MAF translocations including t(14;16), a high-risk CA. Conclusions: We demonstrate that a relationship exists between specific CAs, immunoglobulin isotypes, and clinical presentations in MM. Our data indicate that IgA isotype is significantly associated with intermediate-risk cytogenetics including del(13q) and anemia on presentation, and that light chain disease and renal failure correlate with high risk CAs including del(17p13). These associations between biological and clinical features further support the concept of divergent cytogenetic evolution in MM as being an underlying factor leading to distinctive disease presentations. Disclosures Braunstein: Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Epizyme: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; Verastem: Membership on an entity's Board of Directors or advisory committees; Morphosys: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding.